|Abstract Title:||Comparison and Calibration of Methods for Ambient Reactive Mercury Quantification|
|Presenter Name:||Sarrah Dunham-Cheatham|
|Company/Institution:||University of Nevada, Reno|
|Session:||Special Session - New developments in understanding reactive mercury concentrations and chemistry|
|Co-Authors:||Sarrah Dunham-Cheatham,Seth Lyman,Mae Gustin|
Abstract Information :
The standard method for quantification of ambient reactive mercury (RM), the Tekran speciation system (Tekran), has been demonstrated to be biased low. Because RM can be a dominant form of atmospheric mercury that is deposited and assimilated in ecosystems, it is critical that methodologies be developed that accurately measure RM. Several methods have been developed and tested in various locations in recent years. For this study, four active systems ? 2 membrane-based and 2 dual channel systems ? were co-located alongside a Tekran and operated for one year to assess and compare the performance of each system when sampling the same ambient air chemistry. In addition to the systems, a custom-built automated calibrator was used to assess the accuracy of a dual channel system and membrane measurements. Results indicated that the four systems perform similarly (regression slopes close to 1), and all systems outperform the Tekran (regression slopes < 0.9). Additionally, the calibrator RM recovery was ~95% in both the field and in the laboratory (verified by GC-MS), assisting with further validation of the accuracy of the dual channel system and membrane-based systems. Together, the results demonstrated the four systems provide accurate ambient RM measurements.